


hearts like ice

by capriciouslouis



Category: The Flash (TV 2014)
Genre: Dark Character, F/F, Partner Betrayal
Language: English
Status: Completed
Published: 2019-12-11
Updated: 2019-12-11
Packaged: 2021-02-26 06:48:54
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 13,290
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21759346
Author URL: https://archiveofourown.org/users/capriciouslouis/pseuds/capriciouslouis
Summary: As much as Iris hates Barry Allen, she knows that she needs him. He’s the only way she’s going to get her speed back.Dark!Iris/Killer Frost. After her brief stint as the Flash in 4x16, Iris becomes obsessed with becoming a speedster for good, and nothing can stand in her way.Iris wants Barry's speed. Frost wants Caitlin's body. Together they'll take over the world.
Relationships: Barry Allen/Iris West, Caitlin Snow/Iris West, Iris West/Killer Frost
Comments: 7
Kudos: 47





	hearts like ice

**Author's Note:**

> disclaimer: i love barry a lot and i feel so bad for doing this to him but sometimes an idea just won't let you go, by which i mean to say that i started writing this over a year ago, forgot about it and then finished it within the space of a few weeks bc im kind of obsessed with dark!iris 
> 
> warnings for cheating (iris is married to barry and has an emotional/kind of physical affair with frost so if that's not your jam feel free to click away!)

Every night when she lies in bed, Iris stares up at the ceiling and thinks about killing the Flash.

She knows she used to love him… but that was then. Her life is neatly split into two sections: before the speed-force, and after.

She asked him what it was like, once – before she’d had her one and only taste of the power that thrums through his veins.

_It’s the best feeling in the world,_ he said. Truer words were never spoken.

Now every night, Iris lies and listens to his breathing. Sometimes she hates him so much that her fingers sink into the sheets, twitching with the urge to smother him. But as much as Iris hates Barry Allen, she knows that she needs him. He’s the only way she’s going to get her speed back.

*

Her days are mostly spent doing research, slotting schemes in between the safe, boring little articles she writes to avert suspicion and the hours spent at S.T.A.R Labs safeguarding the speed that Barry is too reckless to protect. She’s smart, but she’s no scientist, and so much of it is hard to get her head around.

Being a journalist is ten percent gumption, ninety percent long, hard slog, and Iris is willing to put in the work – but she has to do it in secret. It would be so much simpler to ask someone like Cisco to walk her through the science, but there’s no way of explaining her new interest for speedster physiology that won’t arouse suspicion, no innocent excuse for studying metahumans whose abilities have siphoned Barry’s abilities, or even slowed him down. There have been a handful of them, and the records are sparse. One was dead before the Flash was anything more substantial than a vague red streak in her blog posts. Another was murdered by Harry, as part of his desperate double-crossing. That case is intriguing; he never erased his records, and she spends hours reading them in the dead of night, eyes roving over notes she is only just beginning to understand. She’s angry that the metahuman killed his doppelganger; she might have been able to replicate the particle accelerator effects on his Earth-1 counterpart. Had him catch the Flash like a fly in resin.

Sometimes, Iris feels like a spider. The world is her web, and everyone around her rests on sticky silk strands. She could snag them and devour them at any moment, and it makes her feel powerful. Since the speed force, few things do.

Iris prides herself on being subtle, flying under the radar. Running her fingers through Barry’s hair, all proud smiles, soft and gentle and unassuming, her hands steady on the marionette strings as she manipulates him and his friends into seeing what they’ve always seen: sweet, dependable Iris who always has Barry’s back, all of them too naïve to notice the knife she’s preparing to stick in it.

Well. Not all of them.

She’s angry by the time she clocks on. If there’s one thing she hates, it’s being slow, and it should have been obvious: the lingering looks, the smirks, the way Killer Frost adds a little extra drawl whenever she speaks to Iris, her smile glittering in a way which says, _‘I know something you don’t.’_

Frost’s not around much; Caitlin has a good handle on her dark side by now. Even so, she’s present enough to be a risk, and Iris is becoming increasingly aware that Frost is dangerous. Worst of all, Iris has no idea whose side she’s on. Self-interest, she can work with. What she _can’t_ work with is a good guy, and she has a nasty feeling that Frost is tipping dangerously towards that side of the line.

“We need to talk,” Iris says one evening.

Everyone else has already left the cortex, congratulating themselves on a job well done. Another meta defeated, another victory for team Flash. Another day of Iris smiling and giving out advice, playing second fiddle to Barry Allen and watching him use the speed that should be hers.

Killer Frost widens her eyes with faux innocence. “ _Do_ we? How nice. Let’s have ourselves a little girly get-together. I’ll paint your nails if you do mine.” When Iris doesn’t respond, she raises an eyebrow. “Well? If you’ve got something to say, spit it out.”

Iris says nothing. The first rule of good journalism is to keep your mouth shut. Most people will dig themselves a hole given the first opportunity; all you have to do is pass them the shovel.

“Never had you down for the shy type,” Killer Frost says. She moves closer, still smiling as if they have a secret. “Have it your way: I’ll go first. You’re up to something.” She leans in. “The question is… what?”

Iris stays quiet. She’s on thin ice; without her speed, she doesn’t stand a chance against Frost. If she screws this up, she’s dead.

“Let’s cut to the chase: I’ve seen you skulking around when you think nobody’s looking, and I’m not the only one who’s noticed. You’ve been leaving some pretty incriminating footprints in the S.T.A.R Labs database. Interesting choice of reading material,” Frost says.

Trying not to think of all the hours she’s spent scrolling through notes about Barry’s genetic make-up, logs of his various injuries and recovery times, along with reams of information she can’t even begin to wrap her head around, Iris keeps her expression blank. “Bedtime reading,” she says. “A little advanced biochemistry sends me right off.”

Frost smirks. “You really should learn to cover your tracks.”

“And if I don’t?”

Frost’s fingers skate over the glass surface of the desk, leaving fractals of ice in their wake. “People might think you’re up to something.”

“And if I am, then what happens?”

“Depends on whether I like the sound of it. If not, then I’ll just kill you. Or I’ll tell the team and have them throw you in the pipeline; whichever seems easiest.”

When Iris is a speedster, she thinks, no one will ever threaten her again. She plays her ace.

“You could,” she says. “Then again, I could also tell them that I’ve seen you skulking around the lab at night when Caitlin thinks that she’s asleep. That you’ve left as many footprints in the system as I have, and the things you’re looking at are just as sinister. Who do you think they’re gonna believe, Frosty? Me or you?”

She enjoys the moment when Frost realizes she’s been played, that she isn’t the only one who was watching. As soon as Iris felt those pale eyes on her, she put her investigative skills to good use. At home in the back of her desk is a thumb drive full of footage of Killer Frost hanging around places she’s not supposed to be, and the team’s trust of her is still balanced on a knife-edge. It won’t take much to make it tip.

Frost doesn’t seem bothered by the equal footing. Her eyes gleam under the lights, and she sounds pleased when she purrs, “Good. You’ve learned how to play the game.”

“Better than you think.”

“Clearly. Then if we understand each other… shall I tell you what I want?”

Iris waits.

“I want my life,” Frost whispers, her voice almost hypnotic with its undertone of whispers, the sound of a thousand voices echoing every word. “Right now, all I have is leftovers. Most of my time is spent cleaning up Caitlin’s messes, helping Team Flash, saving the world. I’m sick of being a spare part. This is my body, my brain, and I intend to take it. No more Mr. Hyde.”

Iris recognises something in her – the determination, the drive to retrieve what has been taken from you. In a way, they want the same thing. Not enough for a conflict of interest – just enough for Iris to understand what burns deep inside of Killer Frost, what makes her blue lips curl and her fists clench. They are mirror images of one another, two lone wolves screaming into the night, and she feels something in her responding to the call.

“Now tell me, Iris West-Allen,” says Killer Frost, leaning in so close that Iris can feel icy breath on her cheek. “What do you want?”

Iris lifts her chin. “I want to be the Flash.”

Frost gives one of her razor-sharp smiles. “I can work with that.”

*

Iris doesn’t like to need people. That is far too much like weakness, and these days weakness is something she cannot abide.

Still, it’s nice to have a partner in crime.

They don’t always have much time together. Caitlin is hard to catch unawares, and Iris never realised how well Killer Frost is kept under wraps until now. Always stifled, pushed to the back of someone else’s head - until Team Flash clicks their fingers and Frost comes running like the world’s deadliest janitor, armed with everything she needs to take out the trash.

If there’s one thing worse than being helpless, Iris thinks, it must be being someone’s lap-dog.

Even with the limited time Frost has, she proves to be worth her weight in gold. She understands what makes a speedster tick, and best of all, she knows how to explain it. Iris no longer has to be in the dark. They sit together, heads pressed together in a dim room, whilst Killer Frost turns the mysteries of the flesh into something comprehensible She sketches differences in physiology on the windows with her finger, an icy diagram that eventually melts away to nothing. No evidence, nothing to give them away. No reason to suggest that they have even been together at all.

Between biology lessons, they discuss strategies. Frost’s problem, unfortunately, is not so easily solved as hers. They both know the Flash’s speed can be taken; it’s happened before on so many occasions that Iris wonders how he manages to sleep at night for fear of losing it.

But Killer Frost’s problems transcend the metaphysical; there is no medication that can keep Caitlin from re-emerging. It is a question of willpower: which of them is strongest? Without a doubt, Iris would have insisted it were the former. But the evidence is impossible to refute; Killer Frost is the interloper. Caitlin calls the shots.

“Maybe the answer _is_ biological,” says Iris one night, as they sit together in the lab. “I mean, Caitlin uses adrenaline to bring you out. Why not use it to keep you here? She comes back whenever you calm down, so why not keep adding more adrenaline to your system? If you’re her defence mechanism, you could just trick your body into a constant red alert.”

Frost rolls her eyes. “I can’t spend the rest of my life keyed up on adrenaline. Firstly, my metabolism works a hell of a lot faster than yours. You can’t anaesthetise me, can’t poison me, can’t suffocate me. My heart-rate can slow to a crawl and I’ll keep on moving. I’m a cold-blooded killer.” She smiles thinly. “Besides that, I have to sleep just like everybody else. That’s usually when she takes over.”

“Right,” says Iris. “You go to sleep as you, and you wake up as…”

“Her,” Frost says bitterly.

Even the thought makes Iris shrink with disgust. She may not have powers right now, but at least she has agency. Killer Frost has nothing.

Her pity slinks across the room like a cat, curls around Frost’s ankles. Frost glares, her eyes glowing even colder.

“ _Don’t_ feel sorry for me.”

“Who said anything about sorry?” says Iris.

Frost keeps her gaze fixed on Iris for a few minutes… but slowly, she looks away.

“So,” she says, scanning through an old case-file about Velocity 9, the speed-force drug that Hunter Zolomon used in the guise of Zoom. “Why the Flash?”

“Excuse me?”

“There are thousands of speedsters all across the multiverse. Why take your speed from him?”

There are dozens of reasons, not least that she’ll never sleep at night without knowing she can outrun anybody in the multiverse who might want to come after her. Of all the speedsters currently living, Barry is the fastest. But, logistics aside, she has a far more personal stake in things than that.

“You can’t honestly say he doesn’t deserve it.”

Frost eyes her shrewdly. “What makes you say that?”

Iris feels her rage rising, a hot kernel of anger like a coal in the centre of a flame. It’s been slowly stoked for years, a white-hot build-up that sometimes sears so hot she thinks she might combust. Sometimes it’s all she can do to keep it contained.

“Look at all the times he’s screwed up,” she says. “He destroys timelines, gets people killed, lets metahumans escape, saves bad people. He was given these powers purely out of chance, good physiology and a well-timed lightning strike. There should be more to being a hero.”

“You think you could do better?” Frost laughs nastily. “Caity told me what happened the one time you got a chance to wear that suit. You got yourself stuck under a girder and had to go crying to the boys to come get you out.”

“Big words, coming from a glorified glove puppet,” snaps Iris. “You’re just a whole lot of cold air with another woman’s head up your ass.”

She’s half expecting to have an icicle thrust through her chest, but Frost seems to enjoy Iris’ anger. She smiles, and a cloud of icy vapour puffs through her teeth.

“And I thought I was supposed to be the cold one.”

Iris doesn’t know what to say to that. She lowers her gaze to a transcript of one of Eobard Thawne’s logs. Gideon’s database contains fifteen years of meticulously catalogued movements, with a generous helping of angst; Thawne didn’t do things by halves. He recorded every single detail of his exile to the letter. It makes for creepy listening, but Iris has earmarked all the entries that sound promising and had them transposed into written transcripts, which she’s slowly working her way through. There’s little information on stealing speed, but plenty on enhancing it. Thawne also liked to record every new skill Barry acquired, which means that she has a comprehensive list of the tricks a speedster should have up their sleeve.

“Do you think you deserve it?” Frost asks. “Barry’s speed?”

Iris has had a long time to think about this – the fact that for all his incompetence and moments of weakness, Barry’s heart is in the right place. He’s a good person. She knows that because she was one too, before all this want consumed her and left nothing but darkness behind. The desire to take and take and take. It has made her stronger, but she knows it hasn’t made her better. She just doesn’t care.

“Do you think you deserve Caitlin’s life?”

Frost’s gaze is unwavering, her eyes the brightest thing in the room. As she answers, she doesn’t even blink. “Caitlin is kind and unselfish, brave and generous. A doctor, and a good one; a woman who has dedicated her life to helping other people. She’s a good person. I’m not. So no, I don’t think I deserve it. But I’m going to take it anyway.”

Iris meets her gaze. “Exactly.”

She goes back to her work, hearing Eobard’s voice in her head, a seductive slither. There was a time when that voice made her shudder, but now she feels that she understands it. Like Iris herself, Eobard was no stranger to that all-consuming obsession that fills her every waking moment. Like Iris, he knew how to be patient, a snake in the shadows, ready to strike.

“How do you sleep at night?” asks Frost. “Lying next to him, knowing you’re getting ready to take away everything he cares about?”

It’s a test. There’s no judgement in Frost’s voice; she just wants to make sure Iris won’t have second thoughts. That she won’t lose her nerve when the moment comes and lose everything she’s worked for.

Iris doesn’t look up from the transcript. “Like a baby,” she says.

*

The conversation changes something between them. Iris doesn’t notice it at first, the shift – but as time goes on, she realises something has given way.

It starts with notes; cool blue post-its, the kind Killer Frost and Caitlin use to communicate. Their messages to one another are littered with barbs, anecdotes from nights out, keeping each other up to speed. Usually, Caitlin’s notes are whole paragraphs, multiple notes in her careful handwriting, whereas Frost writes the way she speaks; a long, lazy scrawl, not letting much on. Her missives drip with sarcasm; most are funny, doing nothing to indicate the cold frustration she feels every minute of the day.

Her notes to Iris are different.

It starts off as a method of sharing research. They pass one another in the hallway, and without even giving Iris a second glance, Frost presses a folded slip of paper into her palm. Iris shivers, cold seeping through her skin and up her wrist, leaving her with goose-bumps. She unfolds the note to find a password and a file reference, which she later looks up on Cisco’s computer, careful to cover her tracks. It turns out to be a blueprint for a discarded project he was working on; a new kind of metahuman containment cuff which, rather than suppressing powers, temporarily siphons them for safer transport. It’s not a permanent solution, and Cisco abandoned the project several months back, but it’s an interesting read.

It’s stupid, and reckless, and makes her heart race, which is proof enough that she should throw the post-it in the trash. But she likes the sweep of Killer Frost’s handwriting, tangible proof of this new thing between them.

She tucks the paper into her purse.

After that it becomes a routine, a steady back and forth like a ping-pong match, a volley of smiles and sly comments, moments that pass between them in an eye-blink. Iris collects Frost’s notes, twisting them into tiny paper birds that she keeps hidden in her desk until they have multiplied into an entire flock, pale secrets that whisper every time she opens the drawer.

In return, Iris spends hours researching split personalities, watching videos of people’s alters and learning what makes them tick. She delves deep into the belly of her research and finds herself resurfacing hours later, eyes aching as she blinks her way back to reality. It’s been a long time since she’s maintained this level of focus, even longer since she has thought of helping anyone except herself.

Perhaps it’s this distraction that blinkers her. It’s easy to forget that she is surrounded by people who are just as smart, or perhaps even smarter than she is – and that they have a bad habit of picking up on things they shouldn’t… like the fact that Killer Frost is spending a lot more time on the surface.

In the beginning, when she first started to emerge, Frost was in and out as swiftly as a needle, straight to the source of whatever problem she was presented with. These days, not so much.

“Killer Frost has been acting pretty weird lately,” Barry comments.

They’re walking down the hallway leading off from the cortex, heading for the cafeteria. Iris needs her coffee; Barry needs another meal, constantly refuelling. That’s another thing Iris likes to dream about – the speedster metabolism. Eating whatever the hell she wants and always having room for more.

She keeps her tone light. “We're talking about a woman who has a sub-zero body temperature and periodically takes possession of the body she shares with one of our closest friends. Define weird.”

“Oh, come on, don’t act like you haven’t noticed. She’s been acting out for a while now. She used to just come out, handle the bad guys and then leave. These days she seems to be spending a lot of time hanging out in the cortex.”

Iris thinks about that. Eye-rolls and smiles exchanged fleetingly across the room. The time Killer Frost approached her late at night, leaned over her shoulder and asked, “What’re you working on?” with her minty-cool breath tickling Iris’ cheek. The time Frost emerged in the middle of a battle and Iris had an iced coffee waiting for her when she got back… the way Frost’s fingers brushed against hers as she took it with a sardonic, “Just the way I like it,” and Iris realised she’d memorised the order without even having to think about it, captivated by the purse of blue lips around a straw.

“Maybe she’s just lonely. I mean, it’s not easy to hold onto friends if you have a history of murdering them all.”

“It’s more than that,” Barry insists. “She’s acting different. Especially towards you.”

“Me?” Iris asks, her heart squeezing. “What do you mean?”

Barry hesitates. “If I didn’t know any better, I’d say she was flirting with you.”

Iris’ heart skips a beat, like a stone being skimmed across a still pond.

“You can’t be serious.”

“I don’t like the way she looks at you,” Barry says, coming to a pause. He folds his arms over his chest. “Maybe I’m imagining things, but it’s not the first time I’ve noticed. She watches you, Iris. Whenever she sees you it’s like you’re the only thing left in the room.”

Iris feels her cheeks grow warm and is glad it doesn’t show. Instead, she smiles teasingly and says, “You, uh, you got a little jealousy there. It’s on your face, right about… here.”

She thumbs an imaginary mark away from the corner of his mouth. A goofy grin breaks out onto his face, like a schoolboy with a crush; he smiles into her touch, resting his cheek against her hand like a cat eager to be petted. Satisfaction radiates through her. It’s so damn easy.

“I’m just saying I find it weird the way she looks at you.”

“You sure you're not just overprotective, Flash?" Iris trails her fingers a few inches down his chest, letting them hover where the emblem usually rests against his ribcage.

She’s already won; she can see it from the soppy smile on his face. “I just wanna make sure nobody's making eyes at my wife.”

“Don't worry,” Iris says. “She’s not my type.”

"Oh? Then what is your type?"

She smiles, sliding her arms around his neck. "You."

*

Killer Frost snorts. “Wow. And he actually bought that?” She tosses a popcorn kernel into the air and catches it in her mouth with a scornful crunch. “Pathetic.”

They’re in Caitlin’s apartment, sat in front of the TV with the volume turned down low. Iris needed to keep Frost updated, and this is safer than the cortex – a guarantee that they won’t be overheard. Also, they get to wear pyjamas. Frost’s belong to Caitlin and, to her intense disgust, have a fluffy polar bear on the front, but Iris kind of likes her this way. Soft around the edges.

"Guess I'm just that good," she says. "But for the record, you might wanna tone it down a little. Barry's not stupid. He knows something's going on."

"Yes, girly movie nights," says Killer Frost. "Nefarious."

"That's the kind of thing I should be doing with Caitlin," Iris points out. "Not you."

"Right. Because Caitlin's the life of the party and I'm just a glorified cold gun. How could I forget?”

"You know I don't think that."

"Of course not. I'm your personal medical textbook. One step up from paging Doctor Google.”

Ouch. That stings, not least because there's truth in it.

"Are you okay?" asks Iris.

Frost crunches aggressively. "Great."

"You don't seem great."

"I'm fine. I don't have feelings, remember? That's Caitlin's area."

"You know you can talk to me," says Iris. "That's what I'm here for."

"I thought you were here to destroy Barry Allen and take away his speed."  
"Well, duh," says Iris. "But you know, we're in this together. You're my friend. If there's something you wanna say, you can tell me."

"Friends," Frost says. "Is that what we are?"

"Well what would you call it?"

It seems to take Frost a long time to process this.

"Coworkers," she says eventually.

"We're eating popcorn and watching _Ten Things I Hate About You._ ”

"Huh," says Frost. “So we are. I've never had a friend before. Always kind of wondered what it felt like."

They fall quiet. Iris thinks about that. The loneliness of having everyone else think of you as lesser. A weapon to wield whenever it's convenient and then hide away out of sight.

"Well," she says. "Now you know."

*

Heeding her warnings, Frost is far subtler after that, keeping her comments and her intense stares to a minimum. Her notes get more creative; Iris finds one hidden in a half filled-out crossword puzzle in the newspaper, and another tucked into an inside pocket of her blazer. Their moments together are more fleeting, but when she has the opportunity, Frost will always brush cool fingers against the small of Iris’ back, or press their knees together under the table as they sit eating lunch in the lounge room, smirking at the way Iris shivers at the contact.

So, despite her teasing, Frost is careful. It’s Iris who screws up.

The situation is pretty standard. Barry’s on the front lines, fighting a meta whilst the rest of them direct him from a safe distance. Judging by the yells and crashes crackling through the comms system, the meta is giving him a run for his money, and he quickly confirms this by shouting for back-up – which, Iris thinks, he does ridiculously often, for the guy who’s supposed to be the city’s most powerful meta.

Cisco grabs his goggles, and they all turn to Caitlin, who pushes her seat back with a shake of her head.

Then her eyes flare silver-white, like a flint being ignited.

Iris feels her heart leap in response to that flicker of colour, a Pavlovian response to Frost’s presence. She glances over at Iris as the pale roots start seeping from the crown of her scalp, all the way down until even the ends are white.

There’s no time for a quick-change, so after looking down and rolling her eyes at Caitlin’s pencil skirt and sensible shoes, Frost reaches out and yanks Iris’ leather jacket off the back of her chair. She throws it on, pulling her hair free of the collar before giving Iris a glittering look that dares her to object.

Iris doesn’t. She’s mesmerised by the contrast between Frost’s pale, silky hair and the stark black of the jacket, the way it offsets her dark lips and translucent skin.

Cisco opens a breach and after stopping to scoop two spare comms units from the desk, the two of them vault through the porthole, which closes behind them in a flash of blue. Pulse hammering, Iris turns her attention back to the screen in front of her, where Barry’s location is monitored by a tracker in the suit. He’s little more than a circle on a blueprint.

Sometimes, Iris enjoys being the overseer. It makes her feel powerful, having a birds’ eye view of the city, giving orders and knowing they will be followed to the letter. Other times, it’s unbearable. The suit has trackers and a comms unit, but no camera; she’s effectively blind, her only awareness of events coming from Barry’s running commentary – most of which is yelling – and the sounds of blows.

“Guys!” shouts Iris. “What’s happening?”

“We can’t hold them off!” cries Barry, and then there’s a screech of static as the connection gutters and dies.

“Barry?”

No response. Iris switches links. “Cisco? Frost?”

She hears blasts, the crackle of Frost’s ice solidifying and crunching as it sets. Cisco cries out in pain; she loses another connection.

“Guys! Talk to me!”

“I –”

Frost’s voice cuts out.

The dead silence on the other end is like a sliced phone line. For a moment Iris sits stunned and staring at the gently pulsating dot on the screen. Barry’s still alive – a quick flicker of a glance at his vitals shows an elevated heartrate, adrenaline spiking in giant peaks. But there’s no telling what’s happened to the rest of them, or how long those signs will stay steady. Whether or not any of them are even conscious, or whether they’re lying vulnerable to attack.

Her hands shake as her fingers fly across the keyboard, trying to find a surveillance camera that will show her what she needs to know. Her ears ring, her voice cracking as she calls their names. They have to be okay, she tells herself, but her breathing is rapid as she keeps calling across the empty airwaves and all she can think of is the way Frost’s eyes flashed to Iris as she pulled on her jacket without thinking twice. The brush of her pale fingers against Iris’ hand whenever she slips a note into her palm.

“Frost?” she asks one last time, her voice cracking.

And then a breach opens a few feet away.

Iris leaps up, the chair careening wildly away from her. Cisco and Barry step through, each holding a metahuman by the arm, like bouncers about to eject a couple of drunks from a club. The two women have meta cuffs around their wrists and are glaring violently at the floor.

Cisco’s goggles are cracked, a fracture like a lightning bolt shooting down one lens. Barry is bleeding from a long gash down his cheek. But Iris’ gaze immediately moves past them, to where Killer Frost is stepping out of the gateway, the last to move through before it seals behind her.

Iris lets out a breath she’d been holding for so long that it hurt.

“Everybody okay?” Barry asks.

“No,” Frost gripes. “I broke a nail.”

Iris’ laugh rips out of her completely unexpected. Her hand flies to her mouth as if to snatch it back, but it’s too late to stop, relief making her giddy. Frost joins her a moment later, her laugh the only warm thing about her.

“I’m sorry,” Iris says, trying to regain her composure. “I was so freaked out, I had no idea what happened.”

“Electricity manipulation,” Cisco says, nodding at one of the metahuman women. “Frazzled the comms system. Smart, actually.”

“Bite me,” the young woman snaps.

“All right, let’s get you down to the pipeline,” Cisco says, steering her away. She makes several angry attempts to shake off his grip on her shoulder before they vanish.

Barry’s eyes are still on Iris. “Are you okay?”

“Fine,” Iris says. “Really.”

He leans in to kiss her on the cheek before leading the second metahuman woman out of the room. As soon as they’re gone Iris sits on the edge of the desk. Frost doesn’t look up, still examining her busted nail. Iris can’t take her eyes off her, the adrenaline slowly leaving her body.

It occurs to her that when the comms went out, she didn’t think even for a second about Barry. Usually her panic would be rooted in the fear that some metahuman had killed him before she could get to him and rip the speed from his cells. Today, though, there was only one person on her mind.

She doesn’t know what to do with these new feelings. They’ve been stirring for a while and she just hadn’t let herself examine them, hadn’t held them up to the light. There are so many things she could say, confessions she could make… but they melt away to nothing on her tongue until all she can come up with is, “Hope you didn’t mess up my jacket.”

Frost shrugs, leather creaking slightly. “Looks better on me anyway.”

Iris imagines her wearing it. Shivers at the thought of Frost walking around in her clothes, stripping off the jacket and dropping it on the floor when she slips into bed that night.

She holds out a hand. “Hand it over.”

Frost slides out of the jacket. When Iris takes it, she notices that coldness clings to the leather. She inhales as she shrugs it on; it smells like smoke, the aftermath of a battle, but also like Caitlin – the soft, unassuming floral scent of her hair. That shouldn’t surprise Iris, but it does. She forgets, sometimes, that they’re technically the same person. Looking at Frost is like looking at the sharp, uneven edge of a mirror and seeing pieces of Caitlin Snow reflected back at her, her edges jagged to the touch.

The thought doesn’t make any of this any easier.

*

By now she should be used to aching; these days, all she does is want. The problem is that it isn’t just the speed-force she craves – it’s Frost, and the feeling isn’t going away. Now she’s noticed it, it’s constant. She feels like a box of matches, feeling the head of a matchstick scrape against her skin over and over again, friction sending sparks crackling. It’s all she can do not to catch fire. The only thing harder than having Frost close and having to keep her hands to herself are the times when Frost is away. It aggravates her that no one else seems to feel the absence, that they’ll all sit and laugh with Caitlin while Iris sits like a child tonguing the space where a tooth used to be, hyperaware of what’s missing. She sees echoes of her in Caitlin’s smile, her laughter a softer version of Frost’s own, and it makes her ache. Like an addict on methadone, taking the lesser hit because it’s easier than cold turkey but still constantly craving. She didn’t think she had room for anything as all-consuming as her desire for the speed-force, but the ache has doubled. This desperate need for things she cannot have.

She begins making excuses to be with Caitlin, hoping for a glimpse of Frost. It doesn’t help. Mostly it just makes her angry because she’s right here waiting and Frost doesn’t show her face, and every time Caitlin blinks at a sharp response or looks hurt when Iris rolls her eyes at something she’s said that would’ve made Frost scoff in disgust, she is reminded that this isn’t enough. That it never will be. Being with Caitlin when she wants Frost is the difference between looking at a photograph and having a real person in front of her – better than nothing, but still not enough.

“Are you mad at me?” Caitlin asks one night while they’re sitting in front of the TV.

It’s a fair question; she’s been irritable all night. When Caitlin invited her she said yes instantly, but ever since she has regretted it. This feels like a betrayal, too reminiscent of the evenings she has spent with Frost in the same way, slowly growing closer to one another and never bridging the gap. Last time she dared to rest her head on Frost’s shoulder and close her eyes, and it was the best kind of not-enough. This is not like that at all.

“Of course not,” Iris says, as if it’s a silly question. “Why would you think that?”

“I feel like things have been weird between us lately.” Caitlin hesitates. “You’ve been a little snappy.”

“PMS,” said Iris. “Makes me super crabby. It was wrong to take it out on you; I’m sorry.”

“You’re sure that’s all it is? I’m worried about you, Iris. It feels like you haven’t been yourself for a while.” Caitlin reaches out to take her hand, her thumb skimming Iris’ knuckles. “You’re my friend, Iris. You know you can talk to me, right? I’m here for you.”

She should say, ‘I know,’ and move the subject onto safer ground. She should make some excuse the way she so often does with Barry. But the reflection of the TV screen is casting a pale glow into Caitlin’s eyes; her hair looks paler, almost honey-coloured in the light. And Iris is suddenly so aware of the closeness between them, the place where her knee is ever so slightly touching Caitlin’s.

It’s a bad idea, and she knows it. But she’s just so lonely, and there’s something in the way Caitlin is looking at her that makes the need reach unbearable heights, makes Iris lean in and kiss her.

It isn’t how she imagined it. Of course it isn’t – Frost is caustic and cold, all sharp edges, where Caitlin is nothing but soft. Her fingers curl in Iris’ hair and the kiss deepens, and Iris’ heart becomes a black hole, because this does nothing to feed the hunger inside her and yet she keeps taking anyway.

She feels it when the kiss changes. There’s a hitch in their rhythm, a momentary pause, and the next breath Iris takes pinches at her lungs. Iris doesn’t want to break the kiss, is too afraid of what happens next, even though her mouth is burning and every intake of breath is so cold that it hurts – and then something sharp and cold as razor wire settles against her throat and she freezes, allowing the pressure to push her back against the couch. With the sharpened icicle cutting into the vulnerable flesh of her throat, Iris swallows and looks straight into Killer Frost’s icy eyes.

“Well,” Frost whispers. “Someone’s been a very naughty girl.”

The pressure on Iris’ throat doesn’t falter; swallowing hurts. Frost takes in the blankets strewn over the sofa, the discarded bottles of nail varnish and the wine on the table, which has already frozen over with icy patterns creeping down the side of the bottle.

“Looks like someone’s been having a party.” She caresses Iris’ throat with the very tip of the blade, making her shiver. “Must have missed my invitation.”

“You’ve been away,” says Iris. “I had to make alternate arrangements.”

Frost’s tone hardens. “Clearly. Did you tell Caity all your little secrets? Find a replacement because I took too long?”

Iris says nothing, because there’s something about Frost when she’s like this that makes her heart beat a little faster, makes all the weeks of waiting worthwhile.

For a moment, Frost continues to scrutinise her. Then she drives the icicle straight down into the couch, making Iris flinch as its point goes straight through the leather, a reminder of how easily it could cut through her skin.

“Get out,” says Frost.

Iris slowly gets to her feet. Frost leans back on the couch, her couldn’t-care-less expression back on.

Her hand is on the doorknob when she turns and says, “I wanted it to be you.”

Frost closes her eyes for a moment. “Don’t mess with me, Iris.”

“Who says I’m messing?”

Iris’ heart is beating harder. It’s not just her who feels this, she realises. It never was.

“Out,” Frost says, her voice low and dangerous.

Slowly, Iris turns the doorknob.

“Kiss Caity again and I’ll kill you.” says Frost.

“Why?” says Iris as she turns around, adrenaline making her daring. “Are you jealous?”

Frost’s eyes flare white.

A blast of ice knocks Iris backwards, a steady, crackling stream that burns as it freezes her solid, plastering her against the door. Iris gasps, splayed out like a butterfly pinned to a card, struggling to free herself. She’s frozen to the neck, which means that she’s helpless when Frost stalks towards her, icy blade back in her hand, and leans in closer than they’ve ever been before tonight.

“You think because I’m cold that I don’t feel? Because I do. I feel all of it. Every minute I’m in possession of this body, every _second_ I’m in possession of this mind, you’re on it.”

Almost lovingly, she traces the blade over Iris’ collarbones.

"You want to know if I'm jealous, Iris? …What do you think?"

"Prove it," Iris breathes. "Kiss me."

She wants Frost to kiss the taste of Caitlin from her tongue, to finally get the chance to worship that dark mouth she's been staring at for so long.

Frost shakes her head. "Can't. If I kiss you it'll kill you."

"Don't care," says Iris.

Frost looks almost amused. "I do."

She presses close up against Iris, their bodies lining up so that Iris swears she can almost feel the curvature of her through the ice; the softness of her chest, the tickle of her hair, her breath so cold that it aches. A shudder rises from deep inside Iris and she makes a sound she should be ashamed of, a desperate cry… one that Frost inhales and then breathes back out even more quietly, like a whisper. Then she takes a step back.

There’s a splitting crack as the ice fractures and crashes to the floor, shattering around her feet. Free of the restriction, Iris shivers.

Frost looks resigned, this time. "Come on," she says. "Let's get you home before either one of us does something stupid." She smiles, then, and it's infectious. Lighter than Iris is used to seeing it. "I'll give you a ride."

They glide across the city on beams of ice, two wraiths flitting so high over the rooftops that Iris feels like they could almost graze the stars. Carving glittering pathways through the air, the moon shining off the ice they leave behind. 

It's not the same as running. But for now, it's enough.

It doesn’t stay that way for long. Frost is in her bloodstream, an addictive substance twisting through her so that every minute spent with her is ecstasy, every minute without her difficult to bear. Every night, she dreams about running. Wakes up next to Barry, cleans her teeth next to him and stares at her reflection in the mirror, the picture of domestic bliss, so pristine and perfect that she could scream.

Comparing what she and Barry once had to what she has with Frost is like comparing an inferno to a birthday candle. The latter, sweet and vanilla, is so easily snuffed out.

There are a thousand stolen moments, more loaded than the ones before. Like the time when Frost reaches out of the Time Vault and pulls Iris inside, surprising her by lifting her up with Iris’ legs around her waist and pinning her up against the wall. Iris hangs on and kisses Frost’s neck until her mouth is swollen and she’s so cold it feels like she’s drowning, every breath turning solid in her lungs.

They have to be so careful. The place Iris most wants to kiss is the place where Frost burns coldest; her mouth, soft and full and forbidden. So much as a brush of lips would be enough to give her frostbite; a real kiss would freeze her to death. When she has her speed back, the vibrations will be enough to keep her warm. Powers or not, Frost’s touch will never stop hurting… but Iris can take a little pain.

She proves it, over the long weeks. When Caitlin re-emerges, allegedly with no memory of what happened between them, and Iris is left alone again. When she watches Frost risk her life over and over again, always the back-up plan. Team Flash uses her like a mallet, a brute force to beat their enemies over the head with, when Iris knows Killer Frost is as lethal as a rapier. As strong as she’s smart, a shadow in the darkness. She should be used with precision, a delicate instrument – not put aside to rust. Yet they take her for granted over and over, the same way they treat Iris. Always so certain she’ll be there to clean up Barry’s mess.

“Don’t you get tired of it?” she asks once, while Frost is applying steri-strips to her cheek.

A rogue meta got past S.T.A.R Labs’ woeful defences – would it kill Barry to install a half-decent alarm system? – and smashed up half the cortex, detritus flying everywhere. Barry showed up and snagged most of the shrapnel from the air before it could touch her, but he couldn’t keep a fragment from slicing up her face. The way he looked at her afterward, all kicked-puppy as he stroked her cheek and probably got a bunch of germs in the wound, made Iris want to roll her eyes. It’s a far cry from Frost’s calm efficiency as she fixes it up, applying each strip with a doctor’s precision. The others complain about being treated by Frost – her bedside manner leaves something to be desired and she doesn’t suffer fools gladly, which means she has little tolerance for anyone who gets themselves beaten up on a regular basis – but Iris doesn’t mind. If getting hurt is the only way for them to spend time together, she’ll take the trade.

“Tired of what?” asks Frost, nudging another strip into place.

_All of it,_ Iris wants to say. She settles for, “Being used.”

“Not really,” says Frost. “The more they come to need me, the more it’ll hurt when I leave.”

*

The good times are worth it, though they’re few and far between. But then there are the bad nights. The times when it’s all too much, when she can’t stand to go back to a home that she no longer fits in, when she feels like Alice in Wonderland pressed against the ceiling of a life that feels far too small for her, Iris does what she needs to do, what she dreams of: she runs.

It’s not enough. Nothing ever is. Her top speed is seven miles per hour and even that is a hair too fast to keep up with, every step feeling more like a fall. Her ears ring, sweat pours down her body, her mouth is so dry that it hurts and yet she doesn’t stop the treadmill, doesn’t lower the pace even when it feels like she’s forgotten how to breathe.

Over the pounding of her feet on the belt, she can almost hear someone calling her name.

“Iris. Iris!”

A blast of ice hits the treadmill crackling fiercely before the mechanisms jam and the belt stutters and stops. Thrown off-kilter, Iris staggers and almost falls – but there is someone there to catch her.

Frost gently lowers her to the floor. Iris’ muscles are water and her hair is stuck to her head, so overheated that when Frost touches her face, it doesn’t even hurt. It’s a relief.

“Why are you doing this to yourself?” Frost whispers.

“I can’t live like this,” Iris chokes. “I can’t.”

“I know. We’ll fix it, I promise. We’ll give you everything you ever wanted.”

“Everything _we_ ever wanted.”

Frost smiles, unusually gentle. “Yeah.”

They lie there for a while. Iris needs to move, but bone-tired isn’t the word.

“Tell me what it’ll be like,” he says. “You and me.”

“We’ll go wherever we feel like,” says Frost. “Do whatever we want.” Her voice cracks. “I’m gonna give you the world.”

Iris rests her head on Frost’s shoulder. “I already have it.”

A moment of silence. Then –

“Iris…”

Somehow, she forces open her eyes. the hair spilling across her shoulder is turning from white to golden brown.

“I’m trying,” Frost says. “I want to be here for you.”

“Honey, it’s okay,” whispers Iris. “I know you have to go.”

Frost snarls, “I _hate_ her.”

“I don’t. She’s a part of you.” Silence. “…Frost?”

Already knowing what she’ll see, Iris looks up into a pair of confused brown eyes.

“Iris?” Caitlin sounds bewildered. “What are we doing on the floor?”

Iris tries to push herself up on shaking arms. Caitlin blinks, a hand to her forehead. She knows they get headaches, sometimes, during the transition. Imagines Frost clawing at the insides of their shared mind, desperate to keep holding on.

“I tripped,” says Iris. “Fell off the treadmill.”

“Oh.” They’re still tangled up together, the fingers of one of Caitlin’s hands interlocked with Iris’. She looks down at their twined fingers without questioning it, trusting as a doe. Her thumb skates over the back of Iris’ hand. “Good thing Frost and I were there to catch you.”

“Yeah,” Iris says quietly. “I guess it was.”

Frost insists Caitlin doesn’t remember what happened between them, that the kiss was lost in the blur of one consciousness into another, but Iris isn’t so sure. She keeps catching Caitlin in moments like this, putting a hand on the small of Iris’ back or resting her head on her shoulder before catching herself with a startled look, as if Frost’s feelings are bleeding through the fault lines.

Maybe she’s just seeing what she wants to see, but sometimes she swears Caitlin will blink with Frost’s eyes or her laughter will come out with sharp edges. Once or twice, she swears she sees fog when Cait breathes out.

Something has shifted. She just isn’t certain what it is.

*

On the day everything changes, they’re all gathered in the cortex, between crises for once. Barry complained they weren’t spending enough time together, so Iris agreed to bring her work to S.T.A.R Labs. All morning she’s been trying to focus while Cisco babbles about some tech he’s working on, creating a blueprint on his tablet, and Barry swings lazily back and forth in an office chair. If she didn’t see his CCPD pay-checks going into their joint account, she’d swear he didn’t have a damn job; he never seems to spend any time there. Meanwhile Frost has been doing research on Caitlin’s laptop, hairdryer on hand to blast the keyboard whenever her touch makes the keys freeze over.

“Hey, can I talk to Caitlin for a sec?” asks Cisco.

“Hmm?” Frost says, tapping away.

“Cait. Lin. You know, the person whose body you’re wearing?”

“Co-habiting,” corrects Frost, taking a sip of coffee, which has already gained a frozen skin on its surface.

“Whatever. I need to talk to her, can you just…?” He waves a hand. “Do the thing, please?”

“You know, it’s not like changing slides on a microscope. We’re talking about switching from one consciousness to another. It’s a little more complicated than just _doing the thing._ ”

“Spare me the lecture,” says Cisco. “If you can’t switch out, at least tell me if she’s listening.”

Frost cocks her head and listens. Several beats pass, and Iris glances up from her computer to see that Frost’s eyes have narrowed. Barry stops swinging on the chair and slowly sits upright, the springs creaking.

“I can’t hear her,” Frost says, perturbed.

“When was the last time we _saw_ Caitlin?” asks Barry. “A few days ago, right?”

Iris realises it’s been longer than that.

“Concentrate,” orders Cisco. “She’s in there somewhere, she’s probably just taking a nap.”

With an irritated sigh, Frost obeys. They all wait. Several minutes pass, and when Frost opens her eyes again, they’re still pale.

“I can’t hear anything. It’s like she’s… gone.”

“She can’t be gone,” Cisco says. “Check again.”

“How exactly do you think this works?” hisses Frost. “You think I’ve got a filing cabinet tucked behind my frontal lobe?”

“I don’t know, Frost, but if there is then you need to work on your organisational system, because there’s only one other person living inside that head of yours and yet somehow you managed to _lose her._ ”

“Okay, let’s all calm down,” Barry says.

Of course, this appears to be the cue for everybody to start arguing at once, talking over one another until it’s almost impossible to pick out one train of thought – but Iris has stopped listening. Her eyes are fixed on Killer Frost, who’s arguing as passionately as the rest of them.

Until, for the briefest of moments, her gaze flicks to Iris and settles on her, and there’s something in that look that brings the whole world into focus.

Later, when Frost passes her in the corridor, Iris catches her arm.

“Are you for real?” she asks in a low voice. “You really can’t find her?”

Barry and Cisco had spent a solid hour poking and prodding her, as if Caitlin were a jack-in-the-box that would come popping out if they hit the right spot. It was a full-scale interrogation, Frost sat in an office chair swinging lazily back and forth while she fielded all their questions and they acted dissatisfied with all of the answers. They had ordered Caitlin’s favourite food, called her name repeatedly, played her favourite songs while Frost twitched in irritation at being subjected to Caitlin’s taste in music. But at the end of all of it, it was still Killer Frost sitting in the chair.

“Nope,” Frost says, her eyes shining brightly. There’s a note of triumph in her voice.

“What did you do?”

Frost shrugs.

“Is it permanent?”

“Guess we’re going to find out,” she says, and then –

“Iris?”

Barry emerges from the corridor, concern pinching between his eyebrows. He slides an arm around Iris’ waist, pulling her towards him in a way that gets on her nerves. Like she’s a balloon on a string, and he’s keeping her from floating too far away.

“It’s getting late,” he says, then adds to Frost, “Keep us updated. If you hear anything from Caitlin…”

“You’ll be the first to know,” Frost says flatly.

Iris knows it’s grating on them both. Barry putting his hands all over her, Frost having to watch.

“We’ll see you in the morning,” he says, oblivious to the way they’re looking at each other.

“Sure,” Frost says, barely an octave above a whisper. “Goodnight.”

The two of them head for the exit, leaving Frost staring after them, her hair gleaming in the light.

“I don’t trust her,” Barry says once they’re out of earshot. “I think she knows more than she’s letting on.” He pauses. “Watch yourself around her, Iris.”

“Yeah,” Iris says. “I will.”

*

The next day, Frost shows up at the lab and Cisco appears to take it as a personal insult. Within the hour, he has her strapped to a chair with half a dozen electrodes stuck to her head, running every single test he can think of. While they wait for the physical results, he tries a psychological tack. Rorschach blots and word association, questions that he keeps repeating long after Frost is tired of giving him the answers. In front of the computer, Iris grips the mouse so hard that the plastic creaks. They’re not even treating Frost like a person, so preoccupied with excavating Caitlin from her subconscious that they forget there’s already someone sitting in the chair.

Frost snaps on day three. Cisco has gone as far as to install cameras in Caitlin's apartment to ensure she and Frost aren't switching in their sleep. He's fast-forwarding through the footage, watching her prowl about the bedroom and eat cereal, having to heat the milk first to keep it from freezing over. It makes Iris feel itchy and it's not even her who's being observed. 

"Hold on a sec," Barry says, though he's already speed-watched the footage three or four times over. "Does her hair look a little darker in that frame to you?"

"You're grasping at straws, Flash," Frost says, sweeping her hair off her shoulder. “If I stopped being me, even for a minute, I would know about it.”

"It doesn't make any sense. You've stayed out for longer periods before, but I thought the two of you figured out a balance."

"Balance," said Frost, "implies we both get an equal share. Caitlin spends way more time at the wheel than I do. Maybe our body is just trying to even out the score."

"No," said Barry, frowning at the screen. "There's more to it than that. There has to be." 

"You're all so eager to be rid of me and get Caitlin back," Frost says. "That hurts my feelings." 

"Pull the other one, Frost," says Cisco, not even glancing away from the screen. "We all know you don't have feelings."

Frost’s lips press mulishly together. She looks away, pretending to be unbothered, but Iris sees the momentary flash of hurt and feels a rush of anger on Frost’s behalf.

“Okay,” Cisco says, stretching and getting out of his chair. “Time to change tactics. I haven’t taken any blood yet, maybe that’ll give us some answers.” He reaches for her arm.

“ _Enough_!”

Frost leaps to her feet and the chair goes spinning backwards, blasted by the icy fog that erupts around her. Mist writhes around her hands, fingers outstretched, her eyes flaring so brightly it almost hurts to look at them. Ice creeps down the walls; their breath all shows in pale puffs. Goosebumps rise on Iris’ bare arms.

“What the hell, Frost!” shouts Cisco.

“I’m through with it,” she hisses. “Poking me and prodding me, trying to pull Caitlin out of me as if I’ve got her hidden somewhere. You wanna search me, Cisco?” She crooks her finger at him, a sharp icicle growing on the tip. “Go ahead.”

Barry slowly rises from his own seat, the way one would face a dangerous animal. No sudden movements.

“Okay,” he says. “I think we all need to calm down.”

“Calm down?” says Frost, her eyes glinting. “I’ve been calm. I’ve spent three whole days being your lab-rat and I’m telling you I’m done.” The icicle on her fingernail grows into a jagged dagger, her fingers curling around it. The room is so cold that it hurts to breathe. Iris can’t take her eyes off Frost, angry and fierce and magnificent.

She has never wanted her more.

“I know,” says Barry. “We’re sorry, okay? Just… drop the weapon so we can talk?”

“You mean so you can snap a set of meta-cuffs on me until I can learn how to be a good girl?” Frost shakes her head. “I’ve played that game. I think it’s time we changed the rules.”

Cisco puts his hand up and Frost throws up her own in response, ready to fire back a blast as soon as he does.

“Don’t do this,” says Cisco. “There are more of us than there are of you.”

“Yes, but you don’t like to play dirty,” says Frost. “I do.”

Her gaze shifts to Iris, still sat rooted to the spot.

“You don’t have to do this,” pleads Barry. “We can figure this out!”

“Thanks,” says Frost. “But I think I’ll take my chances on my own.” And she blows Iris a kiss.

Icy smoke billows from between her pursed lips, filling the room with white fog that swirls thickly around them. Within seconds they can’t see; Iris can just about make out flashes of yellow crackling as Barry flies around the room, trying to grab Frost, but he’s as blind as the rest of them. He starts running in circles and the fog begins dispersing, but in the few seconds it takes to clear the room, Frost has vanished.

Barry runs down the corridor, but Iris already knows it’s futile. Frost is too smart to be caught, speedster or not. She’s slipped through their fingers as easily as the fog she creates to facilitate her escape.

Iris catches sight of her reflection in the monitor. Ice crystals glisten in her hair; numbly, she brushes them away, feels them melting into her palm.

Mere minutes later, Barry returns and confirms what she already knew: Killer Frost is gone.

*

At first, they pour all of their considerable resources into finding her. They pull all-nighters, Cisco’s hair unwashed and sticking to his forehead, a light shadow of fuzz growing on Barry’s unshaven jaw. Iris, with her talent for finding answers where there are none, is the spearhead of the search. She contacts Frost’s associates, spends hours chasing up leads. She feels like a tiger chasing her own tail, finding it’s always just a little out of reach.

Then the days fade into weeks. The trail, lukewarm to begin with, goes cold, and as time passes Team Flash loses their urgency. Frost goes from the topic of constant conversation to an afterthought, and while they continue to work on attempts to find her, with photographs and detailed findings attached to a plastic board, her absence becomes the new norm. Perhaps that’s a good thing. Iris hates the way they talk about Frost – or rather, the fact that they don’t talk about her at all. Their concern is all for Caitlin, the victim of an abduction, ignoring the fact that she isn’t the only one who’s missing.

Not for the first time, Iris thanks her training. As a journalist, no one’s questions her hours of research, the unreasonable hours she keeps, working way into the night. Barry praises her dedication, kisses her goodnight and goes to lap the city, or flops into their bed and lies snoring while, as usual, Iris does the work. She has learned how to tune into whispers and pull the right threads, and eventually she finds a lead worth following up on.

Her investigation brings her to an abandoned apartment building, an ugly grey monstrosity with the clouds just grazing the top of its head. According to the land development records, its destiny is to become part of a luxury hotel chain – but for now it’s simply a derelict building, its pale walls tattooed with graffiti and detritus scattered across the floor.

Debris grinds under her feet as she walks through the room, shining her flashlight into every corner. The place smells of mildew, the walls and ceilings bruised with damp spots. She walks down empty corridors listening, looking, pushing open door after door to look into the rooms where people used to live and every time finding nothing.

She’s searching the third floor when she hears a creak. Freezing, Iris listens hard. Old buildings like this have aches and pains, and the odd groan isn’t unusual – but she knows better than to ignore her instincts, and all of them are saying ‘danger.’ Switching off the flashlight, she tucks it away and pulls out a small handgun. It’s yet another secret she keeps tucked up her sleeve – or rather, into her pocket. Team Flash doesn’t approve of weapons, as if half of team don’t count as weapons in their own right. They call this righteousness. Iris calls it stupidity. Her thumb rests on the safety as she slowly scans the room, tensed and ready.

Something lurches at her from the dark, slamming her into the wall so hard that the breath is knocked out of her and fireworks explode in front of her eyes – and then the barrel of her gun comes up against resistance, the slight give of flesh, and a pair of pale, luminous eyes gleam at her from the darkness.

The safety clicks.

“Boo,” whispers Frost.

The relief that floods her system makes her whole body momentarily weak, not just thankful that she’s not in danger but at the sight of Frost unharmed, the very tangible pressure of her body against hers, Frost’s thigh slotted between Iris’ as if it were made to fit there. She wants to kiss Frost breathless and tell her how much she’s missed her. Wants to tangle her fingers in the soft hair at the nape of her neck and yank her head back, to bite down hard on her throat as a punishment for daring to leave her, and to feel Frost shiver and submit.

Iris does neither of these things.

“Where the hell have you been?” she hisses.

“Aw, why? Did you miss me?”

Iris clenches her fists.

Frost pouts. “Baby, don’t be mad.”

“Don’t be mad? You abandoned me! I thought you were dead.”

“No you didn’t. You and I both know I don’t go down so easy.”

“Where have you been?” Iris asks again.

Frost’s eyes shine out of the darkness. “Living,” she says. “Twenty-four hours a day. Seven days a week. I cracked the code.”

She caresses Iris’ cheek, tucking her hair behind her ear. Iris closes her eyes, shudders in a way that’s unrelated to the cold.

“I had to be certain,” Frost whispers. “That I had really gotten rid of her. That there was no way she could ruin things and betray you. Now I know for certain that Caitlin is never coming back.”

“How’d you do it?” Iris asks. Her heart is hammering at the possibility. “Stay in control?”

Frost shrugs. “Guess I finally found something worth sticking around for.”

Iris closes her eyes as they sting with humiliating tears, and she looks away only for Frost to gently pull Iris’ face towards her, catching the tears that dare to fall so that they turn into icicles and freeze on Iris’ cheeks.

“What’s wrong?”

Iris swallows. “I thought you left me.” It hurts to admit it, her voice cracking, throat sore as vulnerability scrapes each syllable. She waits for the mockery, the mean-girl lilt to Frost’s voice.

But Frost softens. “I wouldn’t leave you, Iris. We’re in this together.”

She leans in and almost, almost kisses Iris on the forehead, her lips brushing over the skin there so faintly that it’s as intangible as a breath. Iris closes her eyes and revels in it. It’s been such a long time since she’s had someone she could rely on. She had forgotten how to felt not to be alone.

“I’m sorry I was gone for so long. I’d have come back to you sooner if I could. But look.” Frost reaches into the inside pocket of her jacket and pulls out what looks like a syringe... if syringes were armoured and as thick as three fingers. The needle is covered, but Iris still holds it gingerly just in case.

"What is it?"

"This," Frost says, tapping it with her nail, "is the answer you've been after. A device that's capable of extracting the speed-force from a speedster's system and transferring it to a secondary host." 

“Where did you get this?” demands Iris, turning the device over and over in her hands, examining it from every angle.

Frost shrugs. “I have contacts. Cisco’s not the only person in this city who knows how to open a breach. There are a couple of metas who owed me a favour.” She tilts her head. “Seems like there are military forces on just about every earth who have been doing everything they can to counteract the speedster problem… guess one of them succeeded.” She smiles, and for once there’s no edge to it. “This is your solution.”

Iris throws her arms around her. 

Frost stiffens for a moment, then shivers, resting her forehead against Iris’. It stings, her skin so cold that Iris can feel her own warm skin sticking to it like her tongue used to stick to ice pops when she was a kid.

Reluctantly, Iris releases her and moves back. Frost’s expression is guarded, her whole body leaning rigidly away. She looks almost pained. 

“You know you can’t touch me,” she says. “Not like that.”

“Yet,” says Iris.

*

That night, Barry is sitting on the couch when Iris walks in through the door.

He twists to look at her and beams. She observes it with a strange, detached feeling, recalling that once upon a time that smile would have made her belly flutter and her heart feel full. Now, she feels nothing.

“Hi,” he says.

Iris finds a warm expression somewhere inside her and puts it on as easily as Barry slips on his cowl. “Hey.”

She walks over to the couch, keeping her pace measured. It takes all of her considerable willpower to keep the exhilaration off her face, tamping down the excitement that threatens to overwhelm her. Everything she has worked towards is finally within her reach, so close she can almost feel it beneath her fingers – the jump of static as adrenaline tingles through her. It’s not quite electricity, but it soon will be.

Iris slips her arms around Barry’s neck, leaning over the sofa and resting her chin on his shoulder. “How was your day?”

“It was okay. I had to testify for a case, which is always stressful, but the guy went down; the evidence against him was overwhelming. Oh, and we thought we had a Killer Frost sighting down-town but it turned out to be a false alarm.”

“That’s too bad.”

She straightens up and puts her hands on his shoulders as if to give him a massage, and Barry sighs and relaxes into it, eyes closed, a blissful smile on his face. She could break his neck right now, or garotte him with the tie he’s abandoned on the arm of the couch. The thought makes her adrenaline spike higher, and Barry melts into her touch with a happy little sigh. He’s so trusting. It fills her with contempt. If she had ever doubted she was making the right decision, the doubt is gone.

“Tell me about the case,” she says, her gaze wandering as she continues to rub his shoulders. Her time is limited; Killer Frost is waiting for her in the lobby, where the chill of her presence won’t give them away.

“Not much to tell,” Barry says. “It was pretty open and shut. The guy’s prints were all over the murder weapon, but they were trying for an insanity plea. Cecile shut ‘em down pretty quickly – ow.” He flinches as her thumb digs into the back of his neck. “That one was a little rough.”

“Sorry,” Iris says, loosening her grip. Her eyes have settled on the vase that rests on a table a few feet away. It was a particularly hideous wedding present, and it will suit her purpose nicely. “You were saying?” One hand leaves his shoulder, slowly reaching for the vase, while the other continues to massage him.

“That was it, really. The defence fell apart within minutes; I barely had to open my mouth. I’m surprised his lawyer was even willing to try. There was no way they were going to get away with it, but it’s crazy what people will do when they’re desperate, huh?”

“Yep,” Iris agrees, and smashes the vase against the back of his head.

It makes a loud cracking sound as it collides with the back of his skull, and Barry goes down hard, collapsing onto the couch with bits of vase clinging to his hair, the ceramic caving in and falling apart in her hand. Immediately Iris seizes the lamp on the table and yanks the plug out of its socket, wrapping the cord around her hand and holding the lamp like a baseball bat, ready for another swing if the first hit proves ineffective – but as she prepares to whack him again, her breathing obscenely loud, there is no crackle of lightning or cry of betrayal. He stays motionless, and when she gives him an experimental nudge with the lampshade, he stays still. Iris moves closer and tries shaking his shoulder, but there’s no response; he’s definitely unconscious, a trickle of blood running down his forehead. She’s not worried about that; his speed-healing will kick in fast enough. That also means that he will wake quickly, though. They have to act fast.

She touches her fingers to the comms unit she stole from S.T.A.R Labs. “Got him,” she says.

Less than a minute later, Killer Frost steps in through the front door, her eyes gleaming as she looks at Barry’s motionless form slumped on the sofa. Walking over to him, she pulls back one of his eyelids and looks into his eye before letting go. “He’s out cold,” she says, her lips twitching at the pun.

Iris puts down the lamp. There will be time for jokes later. Barry has a tendency to turn things around at the last second and she doesn’t intend to let that happen this time. It’s time for someone else to win.

She struggles to lift him – for someone so skinny, he’s like a sack of potatoes – but she manages to get him over her shoulder in a fireman’s lift.

“Ready to go?”

Frost’s eyes glitter. “Ready,” she says.

*

It’s the sound of his breath that alerts her, a sharp hiss. Seconds later, the heart-monitor starts flatlining, unable to cope with his speedster pulse. Wide-eyed, Barry thrashes against the restraints to no avail – and then he looks up and sees her. Walking across the room, she stands over him dispassionately, like a scientist examining a specimen on a slide. Something flat and two-dimensional. 

“Iris?” Barry says, bewildered. He throws his weight against the restraints again, but they hold. They were very thoroughly tested. “What’s going on?”

“We’ve come to take back what’s ours,” says Iris, moving closer. Not quite close enough to touch, though Barry strains against his ties as though he’d like to try. “Killer got her body back. Now it’s my turn.”

His eyes flick across the room to where Killer Frost stands preparing the medical equipment, flicking a syringe and squirting the air bubble out of it. He isn’t afraid yet, just confused. They say it takes an additional seven seconds for a man to recognise a woman as a threat. She wonders how long it takes for a speedster.

“I don’t understand.”

“I’ve come to get my speed,” says Iris.

“Your speed? But -”

“You stole it from me,” says Iris. “I’m just taking back what’s mine.”

Barry laughs disbelievingly, a breathless sound. “You’re not serious.”

Iris holds up the speed-syringe, her heart beating faster. “Deadly.”

Barry turns grey.

She has to touch him, to roll up his sleeve to get to his bare shoulder. She could probably stick the needle anywhere, but she’s reminded of all the times she had shots in the nurse’s office, and they always went for the shoulder. They have all their equipment laid out on a trolley, and she reaches for a sterilising wipe, methodically disinfecting the skin. There’s a risk, transferring fluids like this, but she knows Barry can’t get sick. His body burns off infection like a bonfire, charring germs into nothing.

Pretty soon, her body will be doing the same.

“Iris, this is crazy,” Barry says, still struggling. “I never stole your speed, you never had any speed! You were using _my_ speed; it was an accident! You were never supposed to have it!”

“That’s where you’re wrong,” says Iris. “The speed-force doesn’t make mistakes. That was fate. Your speed was given to me for a reason, and that reason was to show me something I should’ve seen a long time ago. You don’t deserve to be The Flash. I do.

“You were given a gift. The most amazing talent in the world, to move faster than the speed of sound, faster than anything this world has ever seen. Look at how you’ve used it. How many people have died because of you? How many times have you run back in time for a do-over, or because you didn’t like the way things turned out? You are selfish, and you’re irresponsible, and you don’t deserve to do the things you can do. So I’m going to stop you.”

“You can’t,” Barry says, wide-eyed. “Iris, you don’t understand - you don’t have to do this; we can find another way! I can help you, there are other ways we can make you a speedster - don’t do this, Iris!” 

She’s moving closer to him, and he fights harder, thrashing like a worm on the end of a fish-hook. He’s trying to phase through his bonds, but the metahuman cuffs are doing their job; all that speed in his system and no way to access it. Iris grabs his arm.

“Please,” Barry whispers, eyes filling with tears. “I love you, Iris.”

“That’s too bad,” she says. “I haven’t loved you for a _long_ time.”

And she drives the needle into his arm.

It’s less dramatic than she expected. No screaming, or agony. He doesn’t even seem to feel any pain. Not physically, at least. He looks at her as though she’s betrayed him, which Iris supposes she has. Once upon a time that would have bothered her.

Not any more. 

She withdraws the needle. There’s no visible indication as to whether or not the extraction has worked; no lightning crackling in the chamber, no blood or fluid. Wordlessly, she hands over the syringe and rolls up her sleeve, exposing her round brown shoulder.

Killer Frost wipes down Iris’ arm with methodical precision. She presses the tip to Iris’ skin, holding her still with her other hand.

“Ready?”

“Do it,” says Iris.

Killer Frost depresses the plunger.

There’s a flash of pain like a scorpion sting, and Iris flinches as the needle burrows into her arm. For a moment, she stands, heart pounding so hard that she swears it might burst out of her chest - and then there’s a beep, and Killer Frost withdraws the needle, massaging Iris’ arm. She swears she feels it trickling through her veins, whatever it is. But instead of the usual unpleasant coldness of an injection, it feels warm. Like home. 

They stand for a moment. Barry lies on the gurney, staring glassy-eyed into the distance, all the fight gone from him. It’s something that’s always frustrated her, the way he goes like a limp rag-doll whenever he loses his speed, so convinced that it’s the only worthwhile part of him. Iris didn’t make that mistake. Having the speedforce wrestled away from her only made her stronger.

“Anything?” Frost asks in a low voice.

Iris takes a deep breath… and then she feels it.

It explodes through her in a hot rush, taking her breath away with the rightness of it. Her eyes crackle with lightning; purple sparks explode from her fingertips. The speed-force sings through her whole body as though it’s welcoming her home.

“How do you feel?” Killer Frost asks, icy vapour drifting from her in waves. Her eyes are bright as jewels.

Iris turns to her, grinning. “Like I could take over the world.”

Then she takes Killer Frost’s face in her hands and kisses her. 

It’s so cold that it hurts, shooting through her jaw and making her whole face ache. Her hands sting, a thick layer of frost coating her palms. Instinctively, she starts vibrating, the friction from her movement serving to offset the frozen temperature of Killer Frost’s skin. They cling to one another, Iris growing breathless. Killer Frost’s hair is silky as she runs her fingers through it. Her tongue is smooth as glass as it runs across Iris’ lower lip.

They part, both breathless. Iris keeps vibrating ever so slightly as she takes Killer Frost’s hand, barely feeling the sting of the cold. 

She takes one last look at Barry Allen, lying defeated on a hospital gurney, all the fight gone from him. Taken away as easily as his speed.

Then she turns back to Frost, who has never looked so radiant. She’s smiling as though she can never stop - and there are echoes of Caitlin in it, just a whisper of the old softness she’s been struggling to keep at bay so long.

That’s the secret, Iris thinks. That’s how she’s taken over. She stopped fighting the gentler parts of her nature and let them intermingle with the coldness at her core. This is who Killer Frost is - gentle and vicious and cold and loving; everything at once.

“Let’s get out of here,” says Frost.

“Sure,” Iris says. “Piggyback?”

“I will kill you,” Frost says, but she’s grinning. 

“You could try,” says Iris, kissing that smile off her face. Then, quick as a Flash, she sweeps Frost off her feet and into a bridal carry, one cold cheek resting against Iris’ warm one. 

She runs them both out of S.T.A.R Labs and doesn’t look back.


End file.
